MUSCLE DAMAGE IN MDX (DYSTROPHIC) MICE: ROLE OF CALCIUM AND REACTIVE OXYGEN SPECIES
Presented at the AuPS (AHMRC) Symposium Stretch activated ion channels, November 2004. The papers in these proceedings were peer reviewed under the supervision of the AuPS Editor. The papers are being published with the permission of AuPS and were initially published on the AuPS website http://www.aups.org.au
Nicholas P Whitehead, School of Medical Sciences, University of Sydney (F13), Sydney, NSW 2006, Australia. Email: email@example.com
- 1Duchenne muscular dystrophy (DMD) is a lethal, degenerative muscle disease caused by a genetic mutation that leads to the complete absence of the cytoskeletal protein dystrophin in muscle fibres.
- 2The present review provides an overview of some of the physiological pathways that may contribute to muscle damage and degeneration in DMD, based primarily on experimental findings in the mdx mouse, an animal model of this disease.
- 3A rise in intracellular calcium is widely thought to be an important initiating event in the dystrophic pathogenesis. The pathway(s) leading to increased intracellular calcium in dystrophin deficient muscle is uncertain, but recent work from our laboratory provides evidence that stretch-activated channels are an important source of the calcium influx. Other possible routes of calcium entry are also discussed.
- 4The consequences of elevated cytosolic calcium may include activation of proteases, such as calpain, and increased production of reactive oxygen species (ROS), which can cause protein and membrane damage.
- 5Another possible cause of damage in dystrophic muscle involves inflammatory pathways, such as those mediated by neutrophils, macrophages and associated cytokines. There is recent evidence that increased ROS may be important in both the activation of and the damage caused by this inflammatory pathway in mdx muscle.